A.0.05~0.1mg/L B.0.1~0.2mg/L C.0.2~1.0mg/L D.0.5~1.5mg/L
A.>0.1mg/L B.<0.1mg/L C.>0.2mg/L D.<0.2mg/L
A.>6 B.<6 C.>5 D.<5